I have a 2003 Kodiak 450, there is backfire sometimes when you go from full throttle to no throttle, it is the original carb and exhaust, the only thing is the muffler can almost seems empty. does anybody know if it has a baffle inside or its just an open can, also I don't have the tip of the exhaust (spark guard), would that make a difference? I bought it a few months ago runs great except for the odd backfire.
THANKS

 

Try the simple stuff first, just a basic tune up. clean carb,new plug clean air filter and maybe adjust the valves and see where that helps.

 

I would say this may be normal especially if your hard on the throttle and basically letting it snap to the idle position. When you do so, the carb is only allowing fuel to the cylinder via the idle circuit even thought the engine is still at high revs. This along with the fact that you have shut the throttle plate creates a lean mixture which does not get combusted completely in the cylinder. As the unburned gas/air mix leaves the cylinder it builds up in the exhaust system and ignites there creating a backfire.

Try easing off after hard throttle and see if it helps. I know it may not be your style!

 

My 05 Kodiak 400 does this as well.

 

I just cleaned my carb and put a new bowl gasket and needle seat/needle. I cant seem to get my bowl level set where it dont leak out the over flow. I bent the float up slightly but it still leaks a small amount of fuel from the overflow. It eventually drains all the gas out,

 

Where do I go on this forum where some one will actually be on here to chat with.

 

I've an 05 450 and I can't help you on your second problem. Actually I think you had it figured out in your original post with the bad muffler and no end plate. Letting off accelerater with no back pressure will also cause it to back fire. On the carb are you sure you got all the old gasket out or does the bowl have a side that goes to the front etc. . Anyway after bending it your going to have to get the specs and reset it. Good luck.